Potato virus Y (PVY) has been a serious problem of tobacco in several countries and is increasingly becoming a concern in China. Many strains of the virus have been separated on the basis of symptoms, host range, antigenic properties. The identification of PVY strain differences is relevant to plant breeding for disease-resistance and to epidemiological studies. Four strains of PVY were identified from 58 tobacco isolates collected in the main tobacco-growing areas of Northeastern China. The strains were differentiated according to their effect on Nicotiana tabacum cultivars Samsun, NC89, Huangmiaoyu, Xanthi, and White Burley. They were designated PVY^N (veinal necrotic strain), PVY_NS (stem necrotic strain), PVY^C (stripple streak strain) and PVY^O (common strain). PVY^N was the most destructive and caused system veinal necrosis on all test cultivars. PVY_NS caused stem necrosis. PVY^O caused mosaic. PVY^C caused mild mottling of top leaves, yellow blotching and/or ring line of the middle leaves and a general chlorosis of the lower leaves. PVY^N and PVY^Owere transmitted successfully by means of Myzus persicae , whereas positive transmissions of PVY^NS averaged only 30%. But PVY^C could not be transmitted in replicated tests. The results also indicated that PVY^N and PVY^C were the most prevalent and virulent in Northeastern China. They can result in yield reductions of 13% to 100%. PVY_NS was encountered only in northern Liaoning Province, and its incidence appeared to be very low.